Different Dryers for Different Extracts

Good grade extracts are often dried on spray towers. Drum drying and spray drying are the two most common types of dryers used for liquid food products. Because of the their physical characteristics and the ease of thermal damage, malt extract drying requires special modifications of these driers to be done successfully.

Spray towers produce powders that are very fine, due to small droplets required to get these materials to dry in a very short time. This fine particle size is great for dispersing evenly in dry mixes used by bakeries. They are very poor at going into solution by themselves, however, as they tend to ball up and form clumps in water that resisting dissolving. They are also very prone to dusting in the air, which can make a big mess while brewing or handling in a humid environment. If meant to be used in beverages or quickly dissolved, spray dried extracts must typically be agglomerated after drying.

Agglomeration

Agglomeration is a process of slightly rewetting a powder to allow the fine particles to stick together. This creates larger particles with porosity that allow for improved handling and dispersion.

Products dried on filtermats, vacuum band or vacuum drum dryers tend to be coarser and larger in particle size. Because they are broken pieces of a dried cake or agglomerate, they are full of pore spaces which facilitate the entry of water and natural dispersion of the product. Thus these products are naturally agglomerated during the drying process. Drum dried products can look flaky or crystalline, while band and filtermat dried products are more irregular.

After drying, the malt extract is conveyed and packaged in environments containing chilled dried air. If air of too high a relative humidity ever contacts malt extract, it will absorb water and can then either clump, or remelt and solidify to a rock-like consistency. Malt extract is always packaged in bags with complete moisture barriers to prevent this.

Applied Understanding

What is gained by a further understanding of the manufacture of malt extract? A brewmaster should, of course, understand that they should specifically use one manufactured for brewers. (Historically some articles critical of malt extract for brewing focused on malt extract products that were never intended for brewing beer.)

Understanding the process also helps homebrewers better appreciate the care that goes into creating malt extracts with the quality needed to produce beer. Maintaining quality requires constant control of temperatures and time to minimize any ill effects upon the finished product.

This attention to control needs to be continued even after the liquid is produced. One of the most frequent mistakes extract brewers make is using extract that is old or improperly stored. Storage temperature is the critical factor. Liquid extract stored cold will maintain its flavor almost indefinitely ?D stored warm, it will darken noticeably in a few months.

To Boil or Not to Boil

Given that malt extract has already gone through a brewing cycle, many brewers have questioned the amount of additional processing that must be done to successfully brew beer from extract. Specifically, the question of whether worts made from extract require boiling often arises. Understanding their manufacturing process and the main goals of boiling malt extract provides the answer.

There are 5 main “-ations” that brewers are concerned with when boiling their wort or concentrated worts. These are:

•Carmelization (of sugars)
•Volatilization (of DMS precursors)
•Sanitation
•Coagulation (of proteins) and
•Isomerization (of hops)

Carmelization and Volitization: Brewing- grade extract has already undergone a kettle boil and extensive volatilization. Beneficial colors and flavors have been developed from carmelization and Maillard reactions in the kettle boil. Any volatile off aroma or flavors from the grain or DMS precursors have been removed. If the extract is diluted to wort and held at boiling temperatures without proper additional volatilization, additional precursors can be generated. In general, worts from malt extract do not need to be boiled to remove DMS precursors. However, if they are boiled, the boil must be vigorous enough to remove these precursors as more are created when wort is held hot.

Coagulation: All brewing-grade manufacturers remove hot break from their malt extracts. Some manufacturers also remove the cold break.

Sanitation: Though not a sterile product, brewing grade malt extract has gone through a boiling step and has a very low microbial count. It exists as a low water activity product, not permitting growth or spoilage. Contamination is normally so low that simple pasteurization of wort at 160 ºF (71 °C) for 2?C5 minutes is enough to provide reasonable assurance of an uncontaminated finished product. Thus, if using a hopped malt extract or hop extracts, brewers can get away with very short or nonexistent boils, depending upon hop aroma desired and confidence in yeast and sanitation.

Isomerization: Boiling is necessary to isomerize the alpha acids in hops in order to make them soluble. If you are brewing with unhopped malt extract, you will need to boil your hops in wort. However, you can withhold a sizeable amount of your malt extract and add it late in the boil or at the end of the boil.

Now Brew Some Beer

With a better understanding of malt extract production, brewers can better understand when and how to use the extract properly and how to store it. When chosen and used properly, high quality malt extracts can produce world class beer. 

(FROM:BYO.COM)